IUCN collects and hosts spatial species data which is free for download. I'm itching to play with all this data… And, in the end there may arise some valuable outcome:
In the below examples I made a map for amphibian species richness – without much effort. I used a 5×5 km grid (constant areas, provided by Statistik Austria) and amphibian species ranges and intersected this data to yield species numbers per grid-cell. For aggregation of the tables from the polygons produced by the intersection I needed to switch from ArcMap to R because ESRI's “Summary Statistics” only cover MIN, MAX, MEAN, FIRST/LAST… and there is no easy way to apply custom functions. So, I just accessed the dbf that I wanted to aggregate with R and did the calculations there.. then reloaded the layer in ArcMap and was done..
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